Anorexia nervosa, eating disorder characterized by the refusal of an emaciated individual to maintain a normal body weight. A person with anorexia nervosa typically weighs no more than 85 percent of the expected weight for the person’s age, height, and sex, and in some cases much less. In addition, people with anorexia nervosa have a distorted evaluation of their own weight and body shape. They typically consider their emaciated bodies to be attractive or even a bit too fat, have a severely restricted and rigid diet, and have an intense fear of gaining weight. In women the weight loss is accompanied by amenorrhea (failure to menstruate for at least three consecutive months). An estimated 5–20 percent of people with the disorder die as the result of starvation or medical complications that are caused by low weight and a restricted diet.

Anorexia nervosa is one of two major types of eating disorders. The other is bulimia nervosa, which is characterized by binge eating followed by compensatory behaviour such as self-induced vomiting, fasting, or excessive exercise. When the diagnosis of anorexia nervosa is given, a qualified health care professional also will determine whether the patient should also be diagnosed as having one of two types of illness: binge-eating/purging type or restricting type. The binge-eating/purging type is characterized by regular engagement in binge eating (eating of a significantly large amount of food during a given period of time) or purging (self-induced vomiting or misuse of laxatives, diuretics, or enemas) during the current episode of anorexia nervosa. The restricting type is characterized as unhealthy weight loss due to food restriction.

Although some people with anorexia nervosa also engage in binge eating followed by purging, in bulimia nervosa body weight generally remains near or above normal. Approximately 90 percent of all people diagnosed with anorexia nervosa are women, and most report onset of the illness between ages 12 and 25. An estimated 0.5–3.7 percent of women in the United States suffer from anorexia nervosa at some time in their life. However, partial-syndrome anorexia is far more common. Researchers report that close to 5 percent of adolescent girls have this “mild form” of anorexia nervosa, displaying some, but not all, of the clinical symptoms of the disorder.

British physician Sir Richard Morton is credited with the first English-language description of anorexia nervosa in 1689. He reported two adolescent cases, one female and one male, which he described as occurrences of “nervous consumption,” a wasting away due to emotional turmoil. In 1874 anorexia nervosa was introduced as a clinical diagnosis by two different physicians, Sir William Withey Gull of Britain and Charles Lasègue of France. Each emphasized varying aspects of the condition in their clinical reports, yet they both described anorexia as a “nervous” disease characterized by self-starvation. They were the first to recognize the illness as a distinct clinical diagnosis. When Gull reported about his work to the Clinical Society of London, he used the term anorexia nervosa, which literally means “nervous loss of appetite,” to describe the condition. He was the first to do so. Gull’s reports were published by the society the following year, and the term later gained broad acceptance.

Cases of what is today recognized as anorexia nervosa have been documented throughout history, but it was not officially recognized as a psychiatric disorder until 1980, when its incidence increased greatly. Many experts blame the rise in anorexia nervosa on the unrelenting focus in the popular media on young women’s appearance, especially the emphasis on thinness as an ideal. This emphasis is especially common in the cultural standards of beauty in affluent industrialized countries, and anorexia nervosa is far more prevalent in the United States, Europe, and industrialized Asia than it is elsewhere in the world.

Anorexia nervosa usually begins in adolescence or early adulthood. The causes of the illness are multifactorial and include genetic and biological risk factors, developmental factors that may to contribute to a negative subjective body image, a lack of awareness of internal feelings (including hunger and emotions), a family history of eating disturbances, social influence, and psychological factors. Psychological factors can include a range of influences, such as an anxious temperament, perfectionistic or obsessive tendencies, a history of trauma, a co-occurring psychological disorder (e.g., depression, obsessive-compulsive disorder, attention deficit-hyperactivity disorder, and certain personality disorders), and either chronic or acutestress. A family history of alcohol or substance abuse; physical, emotional, or sexual abuse; mental illness; or high parental conflict also have been shown to increase risk. In addition, most cases of anorexia are preceded by an episode of dieting that progresses toward severe food restriction and self-starvation. However, it is not clear whether such dieting behaviour is a precursor to the illness or merely an early symptom.

Research has not identified a uniquely effective treatment for anorexia nervosa in adults. Various forms of psychotherapy and nutrition therapy are used in an attempt to treat it in such cases. For adolescent patients, family therapy that includes parents and sometimes siblings and a family-based treatment approach known as Maudsley therapy appear to be of benefit. Weight restoration is considered the key component to treatment, regardless of the age of onset, as studies show that many of the hallmark symptoms of anorexia are the result of starvation or semistarvation. Hospitalization may be required in cases of extreme weight loss because of its potentially life-threatening nature. People with anorexia nervosa typically are very rigid in their behaviours and are terrified of becoming fat, so the hospital’s medical personnel sometimes may resort to coercive measures such as forced feeding or restricting privileges until there is a gain in weight. The disorder has proved to be challenging to treat with either psychotherapy or antidepressants. Ongoing research is investigating whether other psychotropic medications may be of use for recovery from anorexia. Studies show that about one-half of those who receive treatment for anorexia nervosa remain below their expected body weight even several years after treatment, and many of the rest continue to struggle with eating, dieting, and their body image.

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The disorder anorexia nervosa, from the Latin words meaning "nervous loss of appetite," is characterized by a severe revulsion toward eating that results in extreme thinness and sometimes in death from self-inflicted starvation. The causes of anorexia nervosa are poorly understood, and its treatment is therefore difficult.